Subject: [core] #178: Multiple relation types

From: "core issue tracker" <[email-masked]>
Date: Mon, 05 Dec 2011 15:29:45 -0000

#178: Multiple relation types

 This ticket is to explicitly state that multiple relation types SHOULD NOT
 be included in a CoRE Link Format rel= attribute. There are cases where
 multiple relation types may need to be included for example when an
 RFC5988 link is represented in CoRE Link Format.

 From Esko Dijk's WGLC review:

 ** Relation type: RFC5988 supports multiple relations in one string/entry.
 Should we support this or explicitly (e.g. "SHOULD NOT") exclude this in
 CoRE Link Format context? For example:
        rel="http://example.com/myRelationType1
 http://example.com/myRelationType2 describedby"

 This may be an issue if a constrained client is looking for a
 "describedby" relation using the byte-wise string comparison suggested by
 core-link-format: it would not match to above string unfortunately. Also,
 it causes problems if the "rel" value is stored on a CoRE server as one
 key/value pair and if I would do a query with resource-param = "rel" to
 look for a specific relation type such as "describedby", or "copyright" or
 "http://example.com/myRelationType2". Again, this would not match as it is
 not bytewise identical as defined in core-link-format as the matching
 criterion. One solution would be to state in core-link-format something
 like "the value of a "rel" parameter SHOULD NOT contain more than one
 relation type" i.e. optimize the use of RFC5988 a bit for constrained
 environments by constraining its flexibility. Another solution approach is
 to provide more guidance in how to do the matching in case of the "rel"
 attribute. Yet another solution approach is to allow multiple relations in
 one "rel" value, but add some mandatory implementation guidance that
 multiple, say N, relations should be stored as N separate relations so
 these can be individually found using filtering/querying.

-- 
----------------------------------+--------------------
 Reporter:  zach@…                |      Owner:  zach@…
     Type:  protocol enhancement  |     Status:  new
 Priority:  minor                 |  Milestone:
Component:  link-format           |    Version:
 Severity:  -                     |   Keywords:
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Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/178>
core <http://tools.ietf.org/core/>